Going deeper with regards the total lack of performance of the Linux drivers compared to the Windows drivers, I found out a bit that may be interesting to note. Before I updated the Windows drivers on this laptop, the OpenGL driver version was 6.14.10.6747, I updated the drivers to the 8.3 release (and was when I noticed the huge performance delta), now the OpenGL driver version under Vista is 6.14.10.7412, and oddly enough the OpenGL performance in both Linux and Windows is virtually the same. I tested the very same games on both platforms to make sure there were no other factors at play (the games with which I tested were U99 and Q3), a friend of mine has the exact same laptop and she has not updated the drivers on hers, and sure enough, the peformance delta was there in Windows on both machines, mine scoring notably lower than hers. The driver provider is different, of course, as I used AMD's reference drivers.

The original package version for the driver is 8.401.070727a-051583C-Toshiba, while mine reads 8.471-080225a1-059752C-ATI.

I wonder what did change in the OpenGL code between these two driver revisions that caused the X1200's on these laptops to perform so poorly.